Ultraviolet‐C (UV‐C) radiation has been reported to induce defence responses to pathogens in growing crops and described as a new environmentally friendly method for disease control. However, whether ...the effect of the induced defence mechanisms will persist after the stress imposed by UV‐C is alleviated and how these mechanisms interact with pathogen elicitors upon infection have not yet been investigated. Thus, we inoculated strawberry plants with Mycosphaerella fragariae, the causal agent of leaf spot disease, after 5 weeks of repeated UV‐C irradiation treatment (cumulative dose of 10.2 kJ m−2) and investigated the alteration of gene expression and biochemical phenotypes. The results revealed that UV‐C treatment had a significant impact on gene expression in strawberry leaves and led to the overexpression of a set of genes involved in plant–pathogen interaction. UV‐C‐treated leaves displayed a stronger response to infection after inoculation, with reduced symptoms and increases in accumulation of total phenolics and volatile terpenes, higher expression of pathogenesis‐related proteins and the activity of several defence enzymes. This study presumptively describe, for the first time, the involvement of terpenes, reactive oxygen species, and abscisic acid, salicylic acid, jasmonic acid, and their transduction factors, in the network underpinning UV‐C priming of growing crops for improved protection against pathogens.
In the present study, the priming effect of ultraviolet‐C (UV‐C) on growing strawberry plants was evaluated with respect to interaction of this model plant to the fungal pathogen Mycosphaerella fragariae. We developed a presumptive model based on our data and the available literature. This model propose that the coordination of reactive oxygen species, terpenes, and abscisic acid, salicylic acid, jasmonic acid is at the basis of the network of UV‐C priming of strawberry for their improved protection against a pathogenic fungus. The plant hormones transduction factors, FaPYR1, FaEDS1, FaPAD4, FaAOS, and FaWRKY1, were also highlighted in regulating UV‐C action.
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32.
Embracing 3D Complexity in Leaf Carbon–Water Exchange Earles, J. Mason; Buckley, Thomas N.; Brodersen, Craig R. ...
Trends in plant science,
January 2019, 2019-01-00, 20190101, 2019, Volume:
24, Issue:
1
Journal Article
Peer reviewed
Leaves are a nexus for the exchange of water, carbon, and energy between terrestrial plants and the atmosphere. Research in recent decades has highlighted the critical importance of the underlying ...biophysical and anatomical determinants of CO2 and H2O transport, but a quantitative understanding of how detailed 3D leaf anatomy mediates within-leaf transport has been hindered by the lack of a consensus framework for analyzing or simulating transport and its spatial and temporal dynamics realistically, and by the difficulty of measuring within-leaf transport at the appropriate scales. We discuss how recent technological advancements now make a spatially explicit 3D leaf analysis possible, through new imaging and modeling tools that will allow us to address long-standing questions related to plant carbon–water exchange.
Plant biologists have long resorted to highly simplified 1D or 2D imaging methods and modeling to study fundamentally 3D leaf processes of CO2 and H2O transport.
Recent advances in imaging and computational technology are enabling a data-rich scientific pipeline that integrates leaf 3D measurement, anatomical modeling, and biophysical simulation.
Adopting a 3D approach is not only critical for testing when dimensionality reduction is reliable and accurate, but also promises to deliver insights about: (i) fundamental processes of leaf CO2 and H2O transport and exchange, (ii) the translation of leaf anatomical diversity to functional diversity, and (iii) fine-scale CO2 and H2O exchange processes in broader-scale models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1 (TCP) transcription factors control developmental processes in plants. The 24 TCP transcription factors encoded in the Arabidopsis (Arabidopsis ...thaliana) genome are divided into two classes, class I and class II TCPs, which are proposed to act antagonistically. We performed a detailed phenotypic analysis of the class I tcp20 mutant, showing an increase in leaf pavement cell sizes in 10-d-old seedlings. Subsequently, a glucocorticoid receptor induction assay was performed, aiming to identify potential target genes of the TCP20 protein during leaf development. The LIPOXYGENASE2 (LOX2) and class I TCP9 genes were identified as TCP20 targets, and binding of TCP20 to their regulatory sequences could be confirmed by chromatin immunoprecipitation analyses. LOX2 encodes for a jasmonate biosynthesis gene, which is also targeted by class II TCP proteins that are under the control of the microRNA JAGGED AND WAVY (JAW), although in an antagonistic manner. Mutation of TCP9, the second identified TCP20 target, resulted in increased pavement cell sizes during early leaf developmental stages. Analysis of senescence in the single tcp9 and tcp20 mutants and the tcp9tcp20 double mutants showed an earlier onset of this process in comparison with wild-type control plants in the double mutant only. Both the cell size and senescence phenotypes are opposite to the known class II TCP mutant phenotype in JAW plants. Altogether, these results point to an antagonistic function of class I and class II TCP proteins in the control of leaf development via the jasmonate signaling pathway.
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The role of Rubisco activase in steady‐state and non‐steady‐state photosynthesis was analyzed in wild‐type (Oryza sativa) and transgenic rice that expressed different amounts of Rubisco activase. ...Below 25°C, the Rubisco activation state and steady‐state photosynthesis were only affected when Rubisco activase was reduced by more than 70%. However, at 40°C, smaller reductions in Rubisco activase content were linked to a reduced Rubisco activation state and steady‐state photosynthesis. As a result, overexpression of maize Rubisco activase in rice did not lead to an increase of the Rubisco activation state, nor to an increase in photosynthetic rate below 25°C, but had a small stimulatory effect at 40°C. On the other hand, the rate at which photosynthesis approached the steady state following an increase in light intensity was rapid in Rubisco activase‐overexpressing plants, intermediate in the wild‐type, and slowest in antisense plants at any leaf temperature. In Rubisco activase‐overexpressing plants, Rubisco activation state at low light was maintained at higher levels than in the wild‐type. Thus, rapid regulation by Rubisco activase following an increase in light intensity and/or maintenance of a high Rubisco activation state at low light would result in a rapid increase in Rubisco activation state and photosynthetic rate following an increase in light intensity. It is concluded that Rubisco activase plays an important role in the regulation of non‐steady‐state photosynthesis at any leaf temperature and, to a lesser extent, of steady‐state photosynthesis at high temperature.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Plants maintain the ability to form lateral appendages throughout their life cycle and form leaves as the principal lateral appendages of the stem. Leaves initiate at the peripheral zone of the shoot ...apical meristem and then develop into flattened structures. In most plants, the leaf functions as a solar panel, where photosynthesis converts carbon dioxide and water into carbohydrates and oxygen. To produce structures that can optimally fulfill this function, plants precisely control the initiation, shape, and polarity of leaves. Moreover, leaf development is highly flexible but follows common themes with conserved regulatory mechanisms. Leaves may have evolved from lateral branches that are converted into determinate, flattened structures. Many other plant parts, such as floral organs, are considered specialized leaves, and thus leaf development underlies their morphogenesis. Here, we review recent advances in the understanding of how three-dimensional leaf forms are established. We focus on how genes, phytohormones, and mechanical properties modulate leaf development, and discuss these factors in the context of leaf initiation, polarity establishment and maintenance, leaf flattening, and intercalary growth.
This review summarizes recent advances in the understanding of how three-dimensional leaf forms are established through the regulation of leaf initiation, polarity establishment and maintenance, leaf flattening, and intercalary growth, with a focus on how genes, phytohormones, and mechanical properties modulate leaf development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve "color ...rendering" of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m
·s
for a 16 hd
photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the "color rendering" of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
It was generally thought that aroma of oolong tea resulted from hydrolysis of glycosidically bound volatiles (GBVs). In this study, most GBVs showed no reduction during the oolong tea manufacturing ...process. β-Glycosidases either at protein or gene level were not activated during the manufacturing process. Subcellular localization of β-primeverosidase provided evidence that β-primeverosidase was located in the leaf cell wall. The cell wall remained intact during the enzyme-active manufacturing process. After the leaf cell disruption, GBV content was reduced. These findings reveal that, during the enzyme-active process of oolong tea, nondisruption of the leaf cell walls resulted in impossibility of interaction of GBVs and β-glycosidases. Indole, jasmine lactone, and trans-nerolidol were characteristic volatiles produced from the manufacturing process. Interestingly, the contents of the three volatiles was reduced after the leaf cell disruption, suggesting that mechanical damage with the cell disruption, which is similar to black tea manufacturing, did not induce accumulation of the three volatiles. In addition, 11 volatiles with flavor dilution factor ≥44 were identified as relatively potent odorants in the oolong tea. These results suggest that enzymatic hydrolysis of GBVs was not involved in the formation of volatiles of oolong tea, and some characteristic volatiles with potent odorants were produced from the manufacturing process.
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Leaf senescence can be triggered and promoted by various environmental stressors, developmental cues, and endogenous hormone signals. Several lines of evidence have suggested the involvement of WRKY ...transcription factors in regulating leaf senescence, but the underlying mechanisms and signaling pathways involved remain elusive. In this study, we identified Arabidopsis thaliana WRKY DNA-binding protein 45 (WRKY45) as a positive regulator of age-triggered leaf senescence. Loss of WRKY45 function resulted in increased leaf longevity in age-triggered senescence, whereas overexpression of WRKY45 significantly accelerated age-triggered leaf senescence. Consistently, expression of SENESCENCE-ASSOCIATED GENEs (SAGs) was significantly reduced in wrky45 mutants but markedly enhanced in transgenic plants overexpressing WRKY45. Chromatin immunoprecipitation assays revealed that WRKY45 directly binds the promoters of several SAGs such as SAG12, SAG13, SAG113, and SEN4. Both in vivo and in vitro biochemical analyses demonstrated that WRKY45 interacts with the DELLA protein RGA-LIKE1 (RGL1), a repressor of the gibberellin (GA) signaling pathway. We found that RGL1 repressed the transcription activation function of WRKY45, thereby attenuating the expression of its regulon. Consistent with this finding, overexpression of RGL1 resulted in significantly increased leaf longevity in age-triggered senescence. Taken together, our results provide compelling evidence that WRKY45 functions as a critical component of the GA-mediated signaling pathway to positively regulate age-triggered leaf senescence.
WRKY transcription factors have been suggested to participate in regulating leaf senescence, but the underlying mechanisms and signaling pathways involved remain elusive. In this study, we demonstrated that WRKY45 may function as a critical component of the regulatory network that integrates age and GA signaling to modulate the onset and progression of leaf senescence.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
MicroRNAs (miRNAs) are a kind of short noncoding RNA (20–24 nt), playing versatile roles in plant growth and development. Strawberry generates leaves and flowers with unique features. However, few ...miRNAs have been functionally characterised in strawberry, especially for their developmental regulation.
Here, we identified one ethyl methanesulfonate (EMS) mutant, deeply serrated (des), in the woodland strawberry Fragaria vesca that has wrinkled leaves with deeper serrations, serrated petals and deformed carpels. The causative mutation occurs in the 19th nucleotide of the FvemiR164a mature sequence. Overexpressing FveMIR164A rescued the phenotypes of des/fvemir164a except the petal serrations.
Furthermore, we identified two allelic mutants of FveCUC2a, one target of FvemiR164a, which developed leaves with smooth margins and fused leaflets. Phenotypes of the double mutant fvemir164a fvecuc2a indicated that the two genes act linearly in leaf and carpel development, but synergistically in the development of other floral organs and inflorescence architecture.
This work demonstrates the conserved and novel roles of the miR164-CUC2 module in leaf and flower development in different plant species, and reveals that the 19th nucleotide of FvemiR164a is important for its processing.
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Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to reduced plant growth and dwarfism. However, their ...relationship remains unknown in rice (Oryza sativa). Here, we demonstrated that BR regulates cell elongation by modulating GA metabolism in rice. Under physiological conditions, BR promotes GA accumulation by regulating the expression of GA metabolic genes to stimulate cell elongation. BR greatly induces the expression of D18/GA3ox-2, one of the GA biosynthetic genes, leading to increased GA₁ levels, the bioactive GA in rice seedlings. Consequently, both d18 and loss-of-function GA-signaling mutants have decreased BR sensitivity. When excessive active BR is applied, the hormone mostly induces GA inactivation through upregulation of the GA inactivation gene GA2ox-3 and also represses BR biosynthesis, resulting in decreased hormone levels and growth inhibition. As a feedback mechanism, GA extensively inhibits BR biosynthesis and the BR response. GA treatment decreases the enlarged leaf angles in plants with enhanced BR biosynthesis or signaling. Our results revealed a previously unknown mechanism underlying BR and GA crosstalk depending on tissues and hormone levels, which greatly advances our understanding of hormone actions in crop plants and appears much different from that in Arabidopsis thaliana.
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